I’d like to congratulate Ayanna Pressley on running an excellent campaign and I’m confident that she’ll become a good congresswoman. I do have some questions for some of her supporters, however. As Eugene Scott points out in the Washington Post, there wasn’t any obvious or glaring reason for Boston and Cambridge progressives to want to replace Rep. Michael Capuano unless they thought his race, gender or age were somehow disqualifying.

The triumph Tuesday night of a 44-year-old black woman over a 20-year House member in a Democratic primary election was a stark indicator that Democrats are looking for more representation in a number of factors: In addition to shifts in race and gender, the victory of Boston City Council member Ayanna Pressley over veteran Rep. Michael E. Capuano represented voters’ desire for generational change.

I feel badly for Capuano but that’s not really my concern. People voted for the person they wanted to represent them, and they wanted Pressley. She’s highly credentialed and is a perfectly sensible choice. What I worry about is that people don’t really understand how power works in our system of government, so they are mistaken about how to go about creating change.

Capuano served for twenty years in the House and he still had not become the top Democrat on any committee. In fact, his primary power in the next session of Congress would have probably been as the chairman of the House Transportation Subcommittee on Railroads, Pipelines, and Hazardous Materials. He also had accrued substantial seniority on the House Financial Services Committee, but still only ranked sixth overall. It takes time to climb the leadership ladder. On the more powerful committees, it can take more than two decades to become the chair.

Members of the U.S. House of Representatives don’t have much voting power. Each member’s vote amounts to 0.23% of the total versus a full one percent for senators. They also don’t have any tools to force their bills onto the calendar. It isn’t completely impossible to have some influence without having seniority, but it’s a rare thing and usually involves perhaps just one big idea that might take years to accomplish.

Another thing to consider is that ideological differences within the Democratic caucus play a comparatively minor role, especially when the party is in the majority. While progressives will have reason to hope for some better results if a liberal replaces a very conservative member or if a more socialist-minded representative replaces a Blue Dog, it’s actually very uncommon that this would have any real effect at all. The leadership of the party will bring forward their bills and their strategy and it will almost always pass. The House is big enough to accommodate a few cranks and malcontents but it functions on teamwork, and the Republicans have learned this lesson the hard way.

This is a wordy way of saying that you can think that something tangible will improve if a younger member replaces an older one, or a woman replaces a man, or a person of color replaces an Italian/Irish urban pol, but whatever that thing might be could wind up being less tangible than imperceptible. The idea is right and makes sense, but the way power is distributed, the constituents are more likely to see a net loss when they trade hard-won seniority for youthful energy and fresh perspective.

The main thing Congress does is spend money and only a few people actually have any say in how that money is spent. A secondary thing that Congress does is craft and oversee regulatory structures, and even fewer members have a truly meaningful say in those areas. For a wide array of reasons, individual senators have much more power to influence spending and policy than representatives, and they therefore are much better targets for enforcing ideological purity or changing the political culture on various issues.

A freshman member of the House has virtually no institutional power and they can best serve their constituents back home by making sure the government is responsive when they need some service. It’s a fantasy that they’ll arrive in Washington DC and provide Medicare-for-All, free college and the abolition of ICE.

If the Democrats do as well in the midterms as many now expect, there could be a big enough class of freshmen to have a significant influence on the culture and even the selection of leaders, so I don’t mean to suggest that there’s no promise or hope of change. It’s more that I think politicians tend to overpromise and then disappoint.

Think back to when Barack Obama became president. Members like David Obey (Class of 1968) and Henry Waxman (Class of 1974) were the ones most responsible for enacting Obama’s major legislation. If the Democrats take over Congress in November, the corresponding powers will be Nita Lowey (Class of 1988) and Frank Pallone (Class of 1992). There were thirty-two new Democrats elected to the House of Representatives in 2008, and none of them had any real role in crafting the legislation of Obama’s first two years in office. Many of them were complete washouts like Walt Minnick of Idaho and Larry Kissell of North Carolina. Others like Eric Massa of New York and Alan Grayson of Florida became national embarrassments. A couple of Alabama reps who were elected are now Republicans. But they did at least provide the raw votes the Democrats needed because that’s how the House works–as a team.

If you want to really influence how Congress or the Democratic Party works, you have to have influence over policy and strategy, and that usually means being a member of the leadership team or having control of a committee or critical subcommittee. Replacing a good progressive with twenty years of seniority with a good progressive with no seniority is going to be a loss in the near team–and you might have to measure the near term in decades.

I think what gets lost in our gladiator sport style of politics is that being a member of Congress is a job that involves legislating but most people don’t get to do any legislating at all.  Increasingly, even the committee chairpeople are shut out of the process and have to accept what the leadership creates on their own.  Perhaps there is so much grandstanding because we have 435 House members and the vast majority of them have very little work to do that doesn’t involve figuring out ways to raise money. A citizen probably has a better chance of writing a piece of legislation if they take a job at a think tank or lobbying firm than if they win a seat in the House.

In isolation, the Democratic Party is stronger when it’s younger, more energetic, more dynamic and more diverse. And we’re going to see that happen in a big way when Congress is seated next year.  But people shouldn’t put their faith in the idea that things will be better for them if their own representative is younger or has this or that identity.  If you have an excellent representative with twenty years of seniority, then you should think long and hard before replacing them.  In sports jargon, that’s called entering into the rebuilding stage, which means that you’re not going to seriously contend for the title for a few seasons while you build up fresh talent.

It’s the approach the Kansas City Chiefs took by trading away a Pro Bowl quarterback to the Redskins and committing to a rookie. It’s the opposite of the approach taken by the New York Giants, who decided that a two-time Super Bowl MVP like Eli Manning gave them the best chance to win now.  It will be interesting to see how those strategies play out for each team this season, but that’s not directly applicable here.

Perhaps Ayanna Pressley will bring more to the table even in the short term than Michael Capuano ever could have produced. I’m excited about her new career. But I worry the voters think that change can come more quickly and easily than is ever realistic which is why there is an allure to politicians like Bernie Sanders and Donald Trump who make huge promises without building the institutional support from the actual power players they’ll need to make good.

True, effective legislators are rare and take a long time to develop and I’d take a Henry Waxman over any freshman you can bring at me, every single time.